The present invention relates to visual indicators, and, more particularly, to indicators which display the rate of change of a parameter in non-numerical form.
In new technology avionics systems, instrumentation and displays are becoming more complex as the need for additional functions continues to increase. The avionics systems are required to detect different parameters and to process and display those parameters in a visual form for operator perception. Until recently, many of the measurements were made by mechanical sensors and were utilized or displayed by mechanical elements including rotating dials, meter movements and other electro-mechanical or magnetic devices from which rate or trend information could be perceived. More recently, such information has been detected, processed, and displayed in digital form to improve the accuracy and reduce the space, weight, and power requirements normally associated with prior-known mechanical devices. Digital readouts, however, do not provide rate or trend information in a perceptible form for the pilot.
While digital implementations have significantly increased the ability to include additional displays in a crowded cockpit environment, the amount of displayed information is creating further problems. Each digital readout must be reviewed, sometimes repetitively, to monitor the various measured and calculated parameters. Since only a limited amount of information can be visually perceived and understood by the brain during a given time frame, the increased number of displays also increases the likelihood that information may be missed. In displaying some functions, such as the rate of change of a parameter, continuous monitoring may be necessary at certain times in order to prevent the occurrence of a hazardous situation. In such situations, the constant monitoring required detracts from the observance of other displayed parameters and can thus be as hazardous as no monitoring at all.
In electro-mechanical instruments, the rate of change of a parameter, such as the rate of change of altitude, could be obtained coincidentally from the mechanical indicator (pointer) normally providing the visual output of the measured parameter. For example, the speed of rotation of an altimeter pointer could give an observer a rough indication of the rate of change in altitude or vertical velocity. In such instances, however, great concentration is required to enable the perception of the information. In addition, the instrument fails to provide an easily discernible visual indication of the rate of change limits which would produce an unsafe condition. There is therefore a continuing need for displays which enable such visual perception of parameters, particularly rate of change parameters, which reduce pilot workload during aircraft operation.
Accordingly, the invention has been developed to overcome the shortcomings of the above known and similar techniques and to provide a visual display system and technique capable of improving visual perception of changing parameters.